<?php

/*
 * This file is part of the Symfony package.
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Yaml;

/**
 * Escaper encapsulates escaping rules for single and double-quoted
 * YAML strings.
 *
 * @author Matthew Lewinski <matthew@lewinski.org>
 */
class Escaper {
	// Characters that would cause a dumped string to require double quoting.
	const REGEX_CHARACTER_TO_ESCAPE = "[\\x00-\\x1f]|\xc2\x85|\xc2\xa0|\xe2\x80\xa8|\xe2\x80\xa9";
	
	// Mapping arrays for escaping a double quoted string. The backslash is
	// first to ensure proper escaping because str_replace operates iteratively
	// on the input arrays. This ordering of the characters avoids the use of strtr,
	// which performs more slowly.
	private static $escapees = array( '\\\\', '\\"', "\x00", "\x01", "\x02", "\x03", "\x04", "\x05", "\x06", "\x07", "\x08", "\x09", "\x0a", "\x0b", "\x0c", "\x0d", "\x0e", "\x0f", "\x10", "\x11", "\x12", "\x13", "\x14", "\x15", "\x16", "\x17", "\x18", "\x19", "\x1a", "\x1b", "\x1c", "\x1d", "\x1e", "\x1f", "\xc2\x85", "\xc2\xa0", "\xe2\x80\xa8", "\xe2\x80\xa9" );
	private static $escaped = array( '\\"', '\\\\', "\\0", "\\x01", "\\x02", "\\x03", "\\x04", "\\x05", "\\x06", "\\a", "\\b", "\\t", "\\n", "\\v", "\\f", "\\r", "\\x0e", "\\x0f", "\\x10", "\\x11", "\\x12", "\\x13", "\\x14", "\\x15", "\\x16", "\\x17", "\\x18", "\\x19", "\\x1a", "\\e", "\\x1c", "\\x1d", "\\x1e", "\\x1f", "\\N", "\\_", "\\L", "\\P" );
	
	/**
	 * Determines if a PHP value would require double quoting in YAML.
	 *
	 * @param string $value A PHP value
	 *
	 * @return Boolean True if the value would require double quotes.
	 */
	static public function requiresDoubleQuoting($value) {
		return preg_match( '/' . self::REGEX_CHARACTER_TO_ESCAPE . '/u', $value );
	}
	
	/**
	 * Escapes and surrounds a PHP value with double quotes.
	 *
	 * @param string $value A PHP value
	 *
	 * @return string The quoted, escaped string
	 */
	static public function escapeWithDoubleQuotes($value) {
		return sprintf( '"%s"', str_replace( self::$escapees, self::$escaped, $value ) );
	}
	
	/**
	 * Determines if a PHP value would require single quoting in YAML.
	 *
	 * @param string $value A PHP value
	 *
	 * @return Boolean True if the value would require single quotes.
	 */
	static public function requiresSingleQuoting($value) {
		return preg_match( '/[ \s \' " \: \{ \} \[ \] , & \* \# \?] | \A[ - ? | < > = ! % @ ` ]/x', $value );
	}
	
	/**
	 * Escapes and surrounds a PHP value with single quotes.
	 *
	 * @param string $value A PHP value
	 *
	 * @return string The quoted, escaped string
	 */
	static public function escapeWithSingleQuotes($value) {
		return sprintf( "'%s'", str_replace( '\'', '\'\'', $value ) );
	}
}
